1. Field of the Invention
The present invention relates to an amine compound and a manufacturing method thereof, as well as an electrophotographic photoreceptor using the amine compound and an image forming apparatus having the same.
2. Description of the Related Art
An electrophotographic image forming apparatus for forming images by using electrophotography (hereinafter referred to as an electrophotographic apparatus) has been used frequently such as for copying machines, printers or facsimile units. In the electrophotographic apparatus, images are formed byway of the following electrophotographic process. At first, a photosensitive layer of an electrophotographic photoreceptor equipped in the apparatus (hereinafter simply referred to as a photoreceptor) is uniformly charged to a predetermined potential by charging means such as a charging roller, applying exposure in accordance with image information by exposure means, thereby forming an electrostatic latent image on the photoreceptor. A developer is supplied to the formed electrostatic latent images and a toner as a component of the developer is adhered to the surface of the photoreceptor to develop the electrostatic latent image and visualize it as toner images. Thus formed toner image is transferred by transfer means from the surface of the photoreceptor onto a transfer material such as recording paper and fixed onto the transfer material by fixing means. Further, cleaning is applied to the photoreceptor after transfer of the toner image by cleaning means having a cleaning blade, etc. thereby eliminating the toner and the like remaining on the surface of the photoreceptor not transferred to the transfer material during transfer operation. Then, the surface of the photosensitive layer is charge-eliminated by a charge eliminator or the like to erase the electrostatic latent image.
In recent years, the electrophotography has been utilized not restricted only to the field of the image forming apparatus such as copying machines but utilized also in the field, for example, of printing plate materials, slide films or microfilms for which photography has been used so far, and it is also applied to high speed printers using lasers, Light Emitting Diode (abbreviated as LED) or Cathode Ray Tube (abbreviated as CRT) as a light source. Along with extension of the application range of the electrophotography, the demand for the electrophotographic photoreceptor has become higher and more versatile.
An electrophotographic photoreceptor is constituted by laminating a photosensitive layer containing a photoconductive material on a conductive support made of a conductive material. As the electrophotographic photoreceptor, an inorganic photoreceptor having a photosensitive layer mainly containing an inorganic photoconductive material such as selenium, zinc oxide or cadmium has been used generally. While the inorganic photoreceptor has basic properties as the photoreceptor to some extent, it involves a problem such that the formation of the film for the photosensitive layer is difficult and plasticity is poor, and the production cost is expensive. Further, since the inorganic photoconductive material generally has high toxicity and suffers from great restriction in view of production and handling.
As described above, since the inorganic photoconductive material and the inorganic photoreceptor using the same involve many drawbacks, research and development have been progressed for organic photoconductive materials. Since the organic photoreceptor using the organic photoconductive material has advantages such that the film formation property for the photosensitive material is favorable and the flexibility is excellent, as well as it is light in the weight, excellent in the transparency, and a photoreceptor showing good sensitivity to a wavelength region over a wide range can be designed easily by an appropriate sensitizing method. Thus, the organic photoreceptor has been under development as a predominant candidate for the electrophotographic photoreceptor. Further, the organic photoconductive material has been studied and developed generally in recent years and it has been utilized not only for the electrophotographic photoreceptor but also has been applied, for example, to electrostatic recording devices, sensor materials or organic Electro Luminescent (abbreviated as EL) devices.
While the organic photoreceptor has a drawback in view of the sensitivity and the durability in the early stage, such drawbacks have been improved remarkably by the development of a function separated electrophotographic photoreceptor in which charge-generating function and charge-transporting function are separately attained by different substances. Further, the function separated photoreceptor also has an advantage, in addition to the advantage of the organic photosensitive material described above, that the selection range for the material constituting the photosensitive layer is wide and an electrophotographic photoreceptor having optional characteristics can be manufactured relatively easily. The function separated photoreceptor includes a lamination type and a single layer type. The lamination type function separated photoreceptor is provided with a lamination type photosensitive layer in which a charge-generating layer containing a charge-generating substance for charge-generating function and a charge-transporting layer containing a charge-transporting substance for charge-transporting function are laminated. The charge-generating layer and the charge-transporting layer are formed usually in a state where the charge-generating substance and the charge-transporting substance are dispersed respectively in a binder resin as a binder. Further, the single layer type function separated photoreceptor is provided with a photosensitive layer of a single layer type in which both of the charge-generating substance and the charge-transporting substance are dispersed in a binder resin.
As the charge-generating substance used in the function separated photoreceptor, various substances such as phthalocyanine pigment, squilirium dye, azo pigment, perylene pigment, polynuclear quinone pigment, cyanine dye, squalic acid dye and pyrylium salt dye have been studied and various materials of high light fastness and high charge-generating ability have been proposed.
Further, various compounds have been proposed as the charge-transporting material, for example, pyrazoline compounds (for example, refer to Japanese Examined Patent publication JP-B 52-4188), hydrazone compounds (for example, refer to Japanese Unexamined Patent Publication JP-A 54-150128, Japanese Examined Patent Publication JP-B 55-42380, Japanese Unexamined Patent Publication JP-A 55-52063), triphenylamine compounds (for example, refer to Japanese Examined Patent Publication JP-B 58-32372, and Japanese Unexamined Patent Publications JP-A 2-190862 and JP-A 7-48324) and stylbene compounds (for example, Japanese Unexamined Patent Publications JP-A 54-151955 and JP-A 58-198043, Japanese Examined Patent Publications JP-B 3-39306 and JP-B 4-66023, Japanese Unexamined Patent Publications JP-A 59-95540, JP-A 59-97148, and JP-A 59-191057).
The charge-transporting substances must satisfy the following requirements:    (1) they are stable to light and heat,    (2) they are stable to active substances such as ozone, nitrogen oxide (chemical formula: NOx) and nitric acid generated by corona discharging in discharging the photoreceptor,    (3) they have high charge-transporting ability,    (4) they have high compatibility with an organic solvent and a binder resin, and    (5) they can be manufactured easily and is inexpensive, etc. However, while the charge-transporting substances disclosed, for example, in all of the patent documents described above can satisfy a portion of the demands but have not yet satisfy all of the demands at high level.
Further, in recent years, higher sensitivity has been demanded as the photoreceptor characteristics corresponding to the requirement of reduction in the size and high speed operation to electrophotographic apparatus such as digital copying machines and printers, and particularly high charge-transporting ability has been demanded for the charge-transporting substance. Further, in the high speed electrophotographic process, since the time from exposure to the development is short, a photoreceptor of excellent light responsiveness has been required. In a case where the light responsiveness of the photoreceptor is poor, that is, the decaying speed of the surface potential of the photosensitive layer by exposure is slow, since the residual potential rises and is used repetitively in a state where the surface potential is not decayed sufficiently. Therefore, the surface charges at a potion to be erased are not sufficiently erased by exposure to cause deterioration of the picture quality such as lowering of the image density in an early stage. In the function separated type photoreceptor, since the surface charges of the photosensitive layer at a portion irradiated with a light eliminated by the transportation of the charges generated from the charge-generating substance upon light absorption are transported by the charge-transporting substance to the surface of the photosensitive layer, the light responsiveness depends on the charge-transporting ability of the charge-transporting substance. Accordingly, high charge-transporting ability is required for the charge-transporting substance also with a view point of attaining a photoreceptor having high light responsiveness and capable of forming high quality images also in a high speed electrophotographic process.
Further, for attaining high durability of the electrophotographic apparatus, it is important that the electrophotographic photoreceptor has excellent durability to electric or mechanical external force and can operate stably for a long time. Then, in order to improve the mechanical durability of the photoreceptor, a high charge-transporting ability is required for the charge-transporting substance.
In a case where a photoreceptor is used being mounted on an electrophotographic apparatus, the surface layer of the photoreceptor is inevitably scraped at a portion thereof by a contact member such as a cleaning blade or a charge roller. In a case where the amount of film reduction on the surface layer of the photoreceptor is large, since the charge retainability of the photoreceptor is lowered failing to provide high quality images. Accordingly, for higher durability of the electrophotographic apparatus, it is demanded for a photoreceptor having a surface layer of high mechanical durability resistant to the contact member, that is, having a surface layer of high printing resistance with less amount of film reduction. In order to increase the printing resistance of the surface layer and improve the mechanical durability of the photoreceptor, it is generally necessary to increase the content of the binder resin in the charge-transporting layer used as the surface layer. However, in a case where the content of the binder resin is increased, since the content of the charge-transporting substance in the charge-transporting layer is relatively decreased, this brings about a problem that the charge-transporting ability of the charge-transporting layer is deteriorated and the light responsiveness is lowered. Since the light responsiveness of the photoreceptor depends on the charge-transporting ability of the charge-transporting substance as described above, a particularly high charge-transporting ability is demanded for the charge-transporting substance also for increasing the content of the binder resin thereby improving the mechanical durability of the photoreceptor, without lowering the light responsiveness.
However, the charge-transporting ability of the charge-transporting substances disclosed in all of the patent documents described above is not sufficient and a photoreceptor having sufficient light sensitivity and light responsiveness can not be attained even by the use of such charge-transporting substances. Particularly, sufficient sensitivity and light responsiveness cannot be obtained under a low temperature circumstance and images having an image density enough to practical use can not be formed.
Further, since the photoreceptor mounted on the electrophotographic apparatus is exposed to external light, for example, during maintenance, it is required for the photoreceptor that various characteristics as the photoreceptor are not deteriorated even when exposed to external light.
Further, in recent year, destruction of the global environment by chemical substances has bring about a problem and it has been keenly demanded for appropriately disposing liquid wastes, etc. formed in the course of manufacturing a photoreceptor and in the course of manufacturing materials constituting the photoreceptor. Particularly, since phosphoric reaction reagents used frequently in the course of producing stylbene compounds as disclosed described above, for example, phosphorous oxychloride reagent used in the Vilsmyer reaction for introducing formyl groups into aromatic compounds, heterocyclic compounds or olefins, and phosphorous reagent such as triphenyl phosphine or triethyl phosphate used in the Wittig reaction for converting carbonyl compounds into olefin give large burden to the global environments, disposal of the liquid wastes is troublesome in a case of using such reagents. Accordingly, it is demanded not to use solvents and reagents giving large burdens to the global environment as much as possible in the course of production of materials for the liquid sensitive body and the charge-transporting substances constituting the photoreceptor.